API for Beginners – What Is an API and How to Use It in Web Development
API for Beginners
An API (Application Programming Interface) lets your web app receive or send data to a server or external service. Most modern sites use APIs for forms, orders, user data, and third-party integrations.
What is an API in the Web Context?
In web development, API usually means an HTTP API: you send a request to a URL with a method (GET, POST, etc.) and optionally a body; the server responds with data – often JSON. That’s how the frontend (React, Vue, plain JS) talks to the backend or external services (payments, email, maps).
HTTP Methods in Short
- GET – read data. Doesn’t change anything on the server. E.g. fetching a product list.
- POST – send data, often to create (new order, signup).
- PUT / PATCH – update an existing resource.
- DELETE – delete.
How to Use an API from JavaScript
In the browser you use fetch: const res = await fetch('https://api.example.com/users'); const data = await res.json();. For POST you add options: method: 'POST', body: JSON.stringify({ name: 'John' }), header Content-Type: application/json. In React/Vue you often call fetch in useEffect or on an event (click, form submit).
What to Expect from the Response
The server returns a status code: 200 (OK), 201 (created), 400 (client error), 401 (unauthorized), 404 (not found), 500 (server error). The body is usually JSON – object or array. Always handle errors (check res.ok or status) and show a clear message to the user.
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